Author's Notes for Ch. 18, 'Dominance Hierarchies':

Warning: Potential spoilers ahead if you have not read up to Ch. 18.

Two months. Over three thousand reviews. What can I possibly say, besides thank you?

Still, My Immortal had over eleven thousand reviews. You wouldn't want people to think that fic was better than this one, right?

Sorry about the pace slowing down. I started this fic partially to prove to myself that I could still write thousands of words per day, so long as I was doing something easier than the rationality book I was bogging down on. Now I've started pair writing (that means there's someone else next to me while I write the book) and my productivity has gone way up, but that in turn means I don't have as much free writing energy. But this is still fun, and the future chapters I have planned are too good not to write, so don't go worrying just yet. And hey, still updating pretty damn fast in an absolute sense. Oh, and not to be even more of a review whore or anything, but that thing where you write reviews begging the author to update? It totally works on me. (Coughs.)

Emphasis mine. That is the only instance of anything like that in the notes I saved, though; the only other thing that turned up that I think might have skewed it was the bit where he talked a few times about how HPMOR was the X most reviewed HP fic/fic on ff.net/etc.